The personal information of a user of a portable telephone includes information such as the subscriber's name, age, gender, the state of use of the portable telephone or of mail operation, and the user's position information. The use of this personal information is limited to cases such as when police or firefighters respond to a problem such as an emergency, when a parent checks the position of his child by means of a portable telephone that incorporates GPS (Global Positioning System) for ensuring safety of the child, or when the owner of a portable telephone checks his own current position.
The problem therefore arises that cases in which the personal information of the users of portable telephones can be used are limited to the above-described cases and ordinary people are unable to use the above-described personal information of the users of portable telephones.
As an example of a technique that uses position information of portable telephones, JP-A-2003-122877 discloses a technique for estimating the population of a specific area. In this technique, population is estimated by finding the number of responses of portable telephones geometrically based on, for example, the strength of received radio waves with base stations and then dividing by the diffusion rate of the portable telephones.
However, this is technology of a time when GPS did not exist, and the number of responses is therefore lacking in accuracy. This technology is further limited to simply estimating population and is unable to provide a service in which ordinary people can use various personal information such as the state of operation of a portable telephone, GPS position information, or information provided when making a contract that would be available for use by police or firefighters.